Lubricant



Patented Oct. 17, 1939 PATENT OFFICE LUBRICANT Gus Kaufman and Samuel R. Philson, Beacon, N. Y., assignors to The Texas Company, New -York, N. Y., a corporation of Delaware No Drawing. Application July 9, 1937, g SeriaLNo. 152,757

5 Claims.

This invention relates to lubricants for use under high pressure conditions, and particularly to an extreme pressure lubricant suitable for use in hypoid gears.

;, It has been found that a very desirable lubricant having extreme pressure characteristics may be compounded from lubricating oil, sulfur and a lead soap when these ingredients are combined in the correct proportions and under proper conditions. The sulfur is preferably combined with the oil at temperatures which will produce a sulfurized oil in which the sulfur is loosely combined but sufiiciently bound to prevent separation of the sulfur-n storage. This loosely bound sulfur is essential for the production of our improved'lubricant, whereby it is intended that the sulfur will be in such a combined form that it will perform its maximum efficiency under extreme pressure service conditions. The lead soap is preferably lead naphthenate and is preferably Formula Percent Sulfur 2 Lead naphthenate (commercial) 5 Lubricating oil-80 Saybolt Universal viscosity at 210 F 93 v The lubricating oil and sulfur were chargedv 40 with agitation to a grease kettle, heated to about 350 F. and the temperature maintained for approximately 3 hours. The 'resultant sulfurized oil was then allowed to cool to about 230 ,F. and the lead naphthenate added with continued agi- 45 tat-ion. After thorough mixing, the product was allowed to cool and stored A lubricant so prepared withstood a load of over 6000 pounds according to the method prescribed by the Society of Automotive Engineers.

50 The manner in which the sulfur is. combined with the lubricating oil-is important in order to give a productwhich has the desired extreme pressure characteristics. It has been found that when an oil is drastically sulfurized, for example 55 by heating the oil and sulfur to a. high temperature, with or without pressure, that the sulfur is too tightly bound and the product is unsatis-. tory. We prefer to conduct the sulfurizing treatment at a temperature of about 350-375 F. with a heating time of l-3 hours. Higher tempera- 5 tures, such as in excess of 400 F., produce too much reaction, forming a product which will not withstand the loads encountered in high pressure use. On the other hand, at lower temperatures stability is sacrificed and the sulfur sepaw rates on storage, freezing, or under oxidizing conditions. The reaction temperature is therefore correlated with the time to give a loosely combined sulfurized oil which gives the product extreme pressure properties in addition to the required stability on storage.

It is also important in the manufacture of the product of the present invention to incorporate the lead naphthenate into the product under correct conditions whereby the formation of sludge or precipitation of lead sulfide is avoided. It is desirable to add the lead naphthenate to the sulfurized oil at as. high a temperature as possible in order tov obtain a homogeneous, stable product but the temperature should not reach that at which a sludge or precipitate is encountered. It is preferable to use temperatures of about 220-250 F. and 230 F. being ordinarily about the maximum temperature which can be used although lower temperatures may be employed as long as the resultant product is homogeneous and of satisfactory stability. The lead naphthenate maybe a substantially pure product or a commercial, product containing, in addition 'to the leadnaphthenate, various quantities of 85 hydrocarbon oils or other diluents. The product used in the above example was a commercial product obtained from petroleum and containing lead naphthenate equivalent to approximately 2% lead oxide (PbO). It is preferable that suf- 40 ficient lead naphthenate be used, as a commercial product or otherwise, to produce in the final lubricant a lead naphthenate content of about 1-5%. It is to be understood, of course, that the relative proportions of the sulfur and lubrieating oil may be varied but it is preferable to maintain the sulfur content relatively low, for

example within the range of about 1-3%.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and. therefore only such limitations should be imposed as are indicated in the appended claims. u

I We claim 1 1'. A process for a preparation of lubricants about 350-375 F. for suflicient time to combine the sulfur with the oil in a loosely bound form,

r and thenincorporating lead naphthenate in the sulfuriz'ed oil at a temperature of about 220- 250 F. v '2. A. process for the manufacture of extreme pressure lubricants, which comprises incorporat-' ing sulfur into a lubricating oil while maintaim ing a temperature of about 350-375 Flfor about 1-3 hours, reducing the temperature sn 11 cm;-;..

' sulfur to temperatures above about 350 F. but below 400 F. in suitable proportions and for a mingling lead naphthenate with the resultant product at a temperature of about 230 F.

i 3. A process for the manufacture of lubricants adapted for use in hypoid gears, which comprises sulfurizing a hydrocarbon lubricating oil at a temperature below 400 F. but suificiently high that the sulfur is combined with oil in a loosely bound but sufiiciently combined form that the final product is stable against sulfur separation on storage, and incorporating lead naphthenate in theresultant product at an elevated temperature below 250 F. such that lead sulfide is not precipitated but, sufliciently high to form astable,

subjecting a mineral lubricating oil and sulfur to temperaturesof about 350 to 375 F. thereby forming sulfurized oil containing about 2% sulfur in sufliciently loosely bound form to impart t p the. oil extreme pressure characteristics and sufliciently tightly bound form to impart to the oil stability against separation of sulfur on storagaand then incorporating about 1' to 5% of lead naphthenate into the sulfurized oil at tempera-- tures ofabout 220 to 250 F. to form a homogeneous product substantially free from precrn-tv itated lead sulfide.

5. Aprocess for the preparation of lubricants of the extreme pressure type, which comprises subjecting a heavy mineral lubricating oil and suflicient lengthof time to form a sulfurized oil containing about 13% of sulfur in sufliciently loosely bound form to impart to the oil high extrem pressure characteristics as measured by the SAE method but sufliciently combined form that the final product is stable against sulfur product.

GUS KAUFMAN. SAMUEL R. PHILSON. 

